Liquid trapping device



Dec. 16, 1969 w. o. KRAUSE ET AL 3,433,714

LIQUID TRAPPING DEVICE Filed July 5, 1968 INVENTORS 544/727? a news: Kin 027 4 FJPFFT BY semmesandsemmes ATTORNEYS nited States Patent 3,483,714 LIQUID TRAPPING DEVICE Walter 0. Krause, Chesapeake, Va., and Kenneth W.

Rupert, Mariuette, Wis., assignors to Virginia Chemicals Inc, West Norfolk, Va., a corporation of Maine Filed July 5, 1968, Ser. No. 742,634 Int. Cl. Fb 43/00 US. Cl. 62503 2 Claims ABSTRACT OF THE DISCLOSURE Liquid trapping device of the type used for accumulating liquid intermediate the compressor and evaporator in a refrigerant vaporous return system.

BACKGROUND OF THE INVENTION Field of the invention The present device is designed to protect the compressor in a refrigerant system from the effects of liquid refrigerant returning to it.

In liquid refrigerant systems and heat pumps, a basic problem consists in the unavoidable return of liquid refrigerant to the compressor. Liquid refrigerant can cause the discharge valves to break in the compressor, while diluting the oil in the compressor. The resultant galling or seizing of bearings and other moving parts in the compressor directly affects compressor capability.

Description of the prior art In the prior art devices an accumulator or surge tank has been installed in the suction side of a refrigeration system having inlet and outlet ports at the top of the container. Theoretically, liquid refrigerant will fall to the bottom of the container and vaporize, while the refrigerant vapor proceeds from inlet to outlet, the accumulated liquid refrigerant eventually vaporizing and passing off to the evaporator and the compressor. However, the entrance of liquid or vapor at higher velocity through the inlet creates such a turbulence that much of the liquid will be carried upward towards the exit port. The buffeting of incoming and escaping vapors creates a shearing situation between the two oppositely flowing refrigerant streams and a resultant pressure loss between the inlet and the outlet ports. The resultant pressure drop penalizes refrigeration capacity. In order to provide complete protection for the compressor large volume chambers are required to trap liquid under these conditions.

SUMMARY OF THE INVENTION According to the present invention an accumulator or liquid trapping device of diminutive size is interposed between the compressor and the evaporator, giving greater trapping capacity for refrigerant liquid than in equivalent volume units. Since a smaller volume unit can be used for equal trapping capacity, there is a resultant economy in installation.

The accumulator consists basically of an accumulator chamber having inlet and outlet ports at its top and supporting an eductor tube coaxially with respect to the outlet. The eductor tube extends from the outlet downwardly to the bottom of the chamber. Vapor is introduced through the inlet and, being dead-ended at the bottom of the chamber, commences a swirling action prior to leaving the chamber through the outlet. Simultaneously, refrigerant liquid and oil from the compressor are accumulated in the chamber bottom. The swirling action of the vapor complements liquid accumulation in the bottom of the chamber. The flow of the vapor through the outlet and coaxially with respect to the eductor top induces a Venturi effect which, together with the pressure drop in the eductor tube, induces liquid flow through the eductor tube. Consequently, vaporized refrigerant and oil are returned to the compressor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a liquid refrigeration system;

FIG. 2 is an enlarged vertical sectional view of the proposed liquid trapping device:

FIG. 3 is a horizontal section of the device, taken along section line 33 of FIG. 2; and

FIG. 4 is a perspective view (actual size) of a proposed outlet fitting 28 prior to mounting of the eductor tube 32.

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the invention, liquid trapping accumula tor 10, having inlet port 26 and outlet port 28 supported in its to 34, is positioned intermediate evaporator 16 and compressor 12 within a refrigeration system. Inlet 26 is fed by conduit 20 extending from evaporator 16. Conduit 24 extends from outlet 28 to compressor 12 and conduit 22 extends from compressor 12 to condenser 14. The outlet fitting 33 is so designed as to serve as the outlet port 28 and bracket 30. It is a tubular device with a semi-circular opening in its side to permit the escape of refrigerant vapor. Eductor tube 32 is supported coaxially and inset with respect to outlet 28 by means of bracket 30, so that the eductor tube bottom 35 is offset with respect to the chamber bottom 36. Eductor tube top 31 is inset with respect to the side walls of out let 28 and outlet bottom 29. Bracket 30 includes a vertically downwardly extending semi-circular portion 33 which partially encircles eductor tube 32, shielding the eductor top 31 and the outlet bottom 29 from inlet 26.

Applicants have found that by properly designing the outlet 28, the aforementioned prior art problems can be overcome. Instead of directing the refrigerant vapor directly into the outlet port 28, the outlet fitting of which port 23 is a part is so designed that the vapor must enter at a angle to the vertical axis of the accumulator tank. This creates a swirling action, as shown by directional arrows in FIG. 2, in the liquid refrigerant which is trapped in the chamber bottom 36. This being the case, the turbulence is reduced and almost all of the internal volume of the accumulator chamber 36 will trap liquid refrigerant. This results in the use of a smaller volume for a given application, giving economy to both space requirements and unit costs.

Furthermore, the swirling action of liquid refrigerant results in a decrease in the buffeting of the entering and leaving refrigerant vapor. A lower pressure loss is encountered, thereby inoreasing the operating efficiency of the refrigerating or air conditioning devices requiring one of these devices.

Since the outlet fitting or port 28 is so designed that the refrigerant vapor enters at a 90 angle to the horizontal axis of the accumulator, refrigerant vapor is dead ended at the bottom 36. Port 28 therefore can serve as a holder or mounting bracket for the oil pick up or eductor tube 32. This provides a very effective means of returning any trapped oil to the compressor 12.

The refrigerant vapor flows around the top 31 of the eductor tube 32, creating a Venturi action. This pulls trapped oil into the tube off of the bottom 36. The oil contains a certain amount of dissolved refrigerant, The quantity of dissolved refrigerant is dependent upon the temperature-pressure relationship encountered and is an equilibrium condition. When the oil-refrigerant solution enters eductor tube 32, a certain resistance to flow is encountered resulting in a slight pressure loss in tube 32. This pressure loss will cause some of the dissolved refrigerant to leave the solution. The expanding refrigerant and the Venturi action will push the oil upward out of the tube 32 into the main stream of the refrigerant vapor to return to the compressor 12.

In this manner, a very effective accumulator can be fabricated with economy in space and cost requirements and with efiicient oil return to the compressor without significant penalty to system efficiency due to above normal pressure losses.

Manifestly, the dimensions of the accumulator chamber and the mode of supporting the eductor tube may be varied without departing from the spirit of invention.

We claim:

1. A liquid trapping device of the type used for accumulating liquid intermediate a compressor and an evaporator within a refrigerant system comprising:

(A) an accumulator chamber having a top and bottom with inlet and outlet ports supported in said top at right angles to the bottom of said chamber so as to deadend refrigerant vapors within said chamber;

(B) a bracket fitted to the top of said chamber and extending downwardly from the outlet port into the chamber, said bracket being integral with said outlet extending downwardly from the outlet within the chamber as a half-cylinder baffle having its open side opposed to the chamber wall and its enclosed side interposed between the outlet and inlet; and

(C) an eductor tube supported by said bracket coaxially inset with said outlet and extending from within said outlet to the bottom of said chamber.

2. A liquid trapping device of the type used for accumulating liquid intermediate a compressor and an evaporator within a refrigerant vapor return system comprising:

(A) an accumulator chamber having a top and bottom with inlet and outlet ports in said top, said ports being at right angles to the chamber bottom;

(B) a bracket fitted to the top of said chamber and extending as a half-cylinder downwardly from the outlet port into the chamber, the closed side of said half-cylinder being interposed between inlet and outlet ports and the open side of said cylinder being exposed to the chamber wall; and

(C) an eductor tube supported by said bracket coaxially inset within said outlet, spaced from the walls of said outlet and extending from within said outlet to the bottom of said chamber.

References Cited UNITED STATES PATENTS 2,121,253 6/1938 McGutfey 62503 3,111,819 11/1963 Williams 62503 3,180,567 4/1965 Quiggle 62503 3,212,289 10/1965 Bottom 62503 3,370,440 2/ 1968 Kellie 62503 MEYER PERLIN, Primary Examiner 

